Proceedings Paper

In order to develop LADAR-based sensors that satisfy the cost, size, weight, and power constraints imposed by increasingly demanding systems, new LADAR architectures need to be developed to support requirements in areas such as intelligence, surveillance, and reconnaissance. Knowledge of the spectral reflectivity of objects in a complex scene may prove useful to distinguish object from background, or even to identify partially occluded objects where a full set of identifying pixels may be impossible to measure. We present a novel LADAR architecture to enable spectral reflectivity measurement with a single pulse of a multispectral laser and a single receiver detector, eliminating spectrally dispersive elements which spatially multiplex the return signal to multiple detectors. This is accomplished by exploiting the wavelength-dependent temporal waveforms that arise from stimulated Raman scattering based multispectral laser sources to multiplex multispectral signals inside a single pulse envelope. With knowledge of these effects in a transmitted laser pulse, a measured pulse envelope at the receiver can be modeled as a sum of reflectivity-scaled spectral components, and the individual object reflectivities estimated. The system performance of this architecture is evaluated using measured pulses of a Raman-based multispectral fiber laser to simulate the measurement of objects of interest, including the influence of detector noise. System performance is quantified by calculating the target reflectivity estimation error as a function of signal-to-noise ratio, receiver bandwidth, and receiver sample rate, demonstrating the feasibility of a temporally multiplexed architecture.